A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3528252 can be evenly divided by 1 2 3 4 6 7 9 12 13 14 18 21 26 27 28 36 39 42 52 54 63 78 84 91 108 117 126 156 182 189 234 252 273 351 359 364 378 468 546 702 718 756 819 1,077 1,092 1,404 1,436 1,638 2,154 2,457 2,513 3,231 3,276 4,308 4,667 4,914 5,026 6,462 7,539 9,334 9,693 9,828 10,052 12,924 14,001 15,078 18,668 19,386 22,617 28,002 30,156 32,669 38,772 42,003 45,234 56,004 65,338 67,851 84,006 90,468 98,007 126,009 130,676 135,702 168,012 196,014 252,018 271,404 294,021 392,028 504,036 588,042 882,063 1,176,084 1,764,126 and 3,528,252, with no remainder.
Since 3,528,252 cannot be divided by just 1 and 3,528,252, it is not a prime number.